1. Field of the Invention
The present invention relates to instrumental model analysis and particularly to determination of the relationship between the jaws of a patient in order to analyze malocclusions. More specifically, this invention is directed to apparatus which may be employed for occlusion analysis and especially to such apparatus wherein the position and orientation of the hinge axis of the simulated lower jaw may be adjusted so as to enable various occlusion positions to be simulated. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Description of the Prior Art
For a general discussion of the field of instrumental model analysis as it relates to a study of the jaw relationship of a patient, reference may be had to the present applicant's co-pending application Ser. No. 709,587 entitled "Method and Apparatus for Occlusion Analysis." Devices for instrumental model analysis, such as Arcon articulators, are known in the art. Such prior art articulators include mandibular and maxillary model supports. In the Arcon articulator the mandibular model support comprises a generally T-shaped base plate which supports, on a rear arm, two columns. The spacing between these two columns may be adjusted. The columns, at the ends thereof which are remote from the base plate, are provided with condylar heads. The two aligned condylar heads define an instrumental hinge axis. Centric contacts on the condylar heads permit the implementation of an axis-aligned transfer arrangement, i.e., the hinge axis traced from the patient may be aligned with the instrumental hinge axis of the mandibular support. The mandibular model derived from the patient is secured on a forwardly extending arm of the base plate.
Continuing to discuss the prior art, the assembling of the mandibular model in the articulation-related position on the mandibular support of a prior art articulator by means of a transfer arrangement requires an extremely high degree of precision. The block-fitting of the mandibular model, necessary for this purpose, is performed using special molding compositions. These special molding compositions harden quickly and are relatively stable in dimensional terms. Nevertheless, errors due to residual expansion or distraction of the molding compositions often occur during block-fitting of a mandibular model. As a result of such errors, the hinge axis set by means of the transfer arrangement may be incorrectly aligned with the instrumental hinge axis of the mandibular support of the articulator. A further deficiency incident to the mandibular supports of prior art articulators employed in instrumental model analysis resides in the fact that such supports do not allow for a correction of the instrumental hinge axis as is necessary for adjusting a condylus displacement which is detected, particularly a compression.